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HDMI Redmere cable, Marantz 7005 ground loop hum???

post #1 of 8
Thread Starter 
Hey guys,

I have an XBox 360, Samsung cable box, PS3, Nintendo WII, Sony ES CD player, Oppo 103, Outlaw Audio 7700 amp, Toshiba 50 inch DLP TV, Epson 5020 and a Marantz AV7005 all running into 2 Panamax 5300's. The 3 new components are the Epson PJ, Oppo 103 and Marantz 7005 which I nstalled a few months ago. They replaced a panny PJ, Pioneer BDP51 and Outllaw 990 Pre. With the old system I never had anything more then a slight hum. Right before I added in the new components, the system started to hum louder. I didn't do anything about it as I knew I was changing some of the pieces so I would deal with it then, nothing new was done to the house.

I installed all the new equipment, all new cables, turned it on and the dam hum was still there. I pulled the cablebox in wire, hum gone. Purchased a Jennson transformer isolater, installed, hum gone. Great!! Next time i turned it one, hum came back, equal in all speakers, volume does not effect it, steady buzz. I started pulling wires trying to isolate it. When I pulled the PJ HDMI, buzz stopped. Someone on this forum asked me if the PJ was plugged into the Pannamax, it was not as it is on the other side of the room. I ran a cord over from the PJ to the Panamax and the hum stopped again. I then ran SJ cord 14/3 from the PJ to the Panamax, turned everything on, hum was back, this time in only the rear right speaker. I am running a 5.2 set up.

I pulled all the cables etc and couldn't find what was making the buzz. I switched the wire from one speaker to the other, the buzz followed, it was in that wire. At this point I was so pissed off I decided to run a dedicated 20 amp circuit from my panel to my componenets. Using 12-3 i ran the circuit with an isolated ground and used that type of recepticle. Plugged everything into that circuit, still buzzes from the rear right speaker.

I was playing around with the back of the Marantz 7005, I pulled out HDMI 2 cable which runs to the Toshiba TV, buzz still there, when I went to put it back in, I was off a little and the HDMI end was tapping the back of the 70005, I heard static and all of a sudden, bam, the buzz went quiet. I plugged back in the HDMI cable to HDMI out and the buzz was still gone. I shut down, turned it back on, buzz back, still out of the rear right surround speaker.

Again, I tap the cable to the back ot the Marantz, some static and the buzz goes quiet again. WTF!!! If the HDMI cable taps a back screw on the Marantz, the buzz stops also. Almost like a capacitor is discharging.

What is going one, can someone please help me on this one, I am at a loss here. Brand new 20 amp circuit, isolated ground, nothing on the line but my home theater, back right speaker buzzing kind of loud, then tap HDMI out 2 from Marantz, static then quiet???

I tried it with HDMI 1 out of the Marantz and nothing. This is the one to the PJ which is a Monoprice 60 foot Redmere cable. It is the only Redmere cable I am using.

Sorry post is so long, I tried to keep it as short as I could.


I also posted this in the Amp/Pre forum.

post #2 of 8
As I mentioned before, finding a ground loop quickly becomes a science fair project. It's easy to go off on many tangents and not easy to find the source.

I would suspect that adding another 20Amp circuit didn't help (and may have hurt). The problem you are getting is that your ground is not the same throughout the circuit.

The Marantz is where the 60 Hz noise is getting into your system. The problem, you are finding out, is figuring how it is getting into the system.

One thing I hadn't seen (or don't remember), if you disconnect all of the speakers can you still generate the hum? (listen through headphones) Then when you connect the speakers back again does the hum only start when you add the right rear speaker?

Also, if you can borrow another receiver, does a different receiver generate a hum? If a different receiver does not generate the hum, that would then indicate a ground problem inside the Marantz.

Remember anytime you touch metal in this circuit you are creating another ground.

The only other suggestion would be to either trace your house grounds or have an electrician do it. Mulitple grounds in the house could also cause a problem. Check for cable lines or satellite dish lines that are improperly grounded.

I know this isn't easy and I really wish you luck. It can be maddening.
post #3 of 8
if the hum was there before all these changes, I wonder if a filter capacitor or other problem is going bad in your amp?
post #4 of 8
Thread Starter 
Thanks guys, let me ask this. Why is the hum only coming out of one speaker and why when I touch only that one HDMI cable to the back of the Marantz, does the buzz stop? Then I can plug the HDMI cable back in, and the noise stays away still. Shut if off and turn it on, noise is back?

Everything is on one circuit.

post #5 of 8
why oh why??? the question of the ages... :-) "black box testing" is unlikely to answer the question with any "meat". Why? because it is likely one channel on your amp has a circuit issue.... what's the issue? that's where you need to open the "black box" :-) likely a leaky capacitor somewhere in the circuit. Why is it "repaired" with a "touch" of a given cable.... well try connecting the other cable to exactly the same equipment (ie. TV) and you will likely get the same result. It is likely that the TV's grounding is / was used in some form to cause something ("burn thru", "full charge",???), look into the "black boxes"... ie. full circuit analysis.... or as Andy says... science project. ... :-)
post #6 of 8
The more I'm thinking about this more trying a different preamp/amp is the best way to pin this down. Eliminate the apparent problem and see if it turns out to actually be the problem.

In terms of touching the HDMI cable, a few things happen when you do that. One is you've obviously created a new signal path to yourself (assuming you are touching something conductive). Two is you've put pressure on the connector and the underlying surface board. Three you've added a small amount of heat (from your hand and that the unit is still running). There is probably four and five that I can't think of right now. But touching a cable can change a few parameters. If you do have a cracked solder issue or something like that (not that I am saying that), just that pressure on the board could close the solder and then over a small amount of time it opens back up again.

For what it is worth, there is at least one other electrical chase that's even worse - figuring out the cause of intermittent AHCI circuit breaker trips. May you never have to worry about those.
post #7 of 8
Thread Starter 
Here is something else that is happening. I have a Stewart electric screen with a 12 volt trigger. I use one of the 12 volt outputs out of the Marantz to trigger the screen. I pulled the 12 volt plug out of the Marantz and the hum got much softer in the rear right speaker. I left it unplugged and touched the 12 volt wire at the screen, went to pull it out, a small static charge hit the screen casing and the hum came back.

So now i can make the hum go and come with static hah. I am really gong nuts here.

I do not have another piece of equipment to swap out. I only have some older receivers but they do not have HDMI switching on them. I am not sure if I said, but I am using XLR balanced inputs. Maybe I should try regular?

I keep reading more and more about the Marantz 7005 having a hum with a lot of people who own them, also on the Outlaw Audio forum there were some on there.

I am thinking of return it and trying another one?

Thanks for the help so far guys.

post #8 of 8
The discharge concerns me since that could be a sign of some leakage. It might be that trying a different AVR design is the best way to solve this but the only way to know would be to try it.
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